public class PolyLine {
  // Construct a polyline from an array of points
  public PolyLine(Point[] points) {
    if(points != null) {                                               // Make sure there is an array
      for(Point p : points) {
        addPoint(p);
      }
    }
  }

  // Construct a polyline from an array of coordinates
   public PolyLine(double[][] coords) {
     if(coords != null) {
       for(int i = 0; i < coords.length ; ++i) {
         addPoint(coords[i][0], coords[i][1]);
      }
    }
  }

  // Add a Point object to the list
  public void addPoint(Point point) {
    ListPoint newEnd = new ListPoint(point);                           // Create a new ListPoint
    if(start == null) {
      start = newEnd;                                                  // Start is same as end
    } else {
      end.setNext(newEnd);                                             // Set next variable for old end as new end
    }
    end = newEnd;                                                      // Store new point as end
  }

  // Add a point defined by a coordinate pair to the list
  public void addPoint(double x, double y) {
    addPoint(new Point(x, y));
  }

  // String representation of a polyline
  @Override public String toString() {
    StringBuffer str = new StringBuffer("Polyline:");
    ListPoint nextPoint = start;                                       // Set the 1st point as start
    while(nextPoint != null) {
      str.append(" "+ nextPoint);                                      // Output the current point
      nextPoint = nextPoint.getNext();                                 // Make the next point current
    }
    return str.toString();
  }

  private ListPoint start;                       // First ListPoint in the list
  private ListPoint end;                         // Last ListPoint in the list
}